SUMMARY
Under the assumption that isospin TT is a good quantum number, mirror transitions Tz=+1?0T_{z }= +1 \to 0 and Tz=-1?0T_{z }= -1 \to 0 were studied in A=34A = 34 isobars, where TzT_{z} is zz component of iospin TT and is defined by Tz=(N-Z)/2T_{z} = (N-Z)/2. With a high energy resolution of 35 keV in 34^{34}S(3He,t)34(^{3}He,t)^{34}Cl reaction measurement at 0°0^{\circ} scattering angle and at an incident energy of 140 MeV/nucleon, strengths of Fermi and Gamow-Teller (GT) transitions from the Jp=0+J^{\pi } = 0^{ + }, Tz=+1T_{z }= +1 ground state of 34^{34}S to the Jp=1+J^{\pi } = 1^{+ }, Tz=0T_{z }= 0 excited states in 34^{34}Cl were determined up to excitation energy (Ex)(E_{x}) of 7.087.08 MeV. The corresponding isospin-symmetric transitions connecting Tz=-1T_{z }= -1 and Tz=0T_{z }= 0 states can be studied in the 34^{34}Ar ß+\beta ^{ + } decay. The strengths of the (GT)±(GT)_{\pm } transitions were compared up to the excitation energy of 3.1 MeV. A good agreement was observed for two strong transitions to 2.5802.580 MeV and 3.1293.129 MeV states, while a disagreement about 45%45\text{%} was observed for a weaker transition to 0.6660.666 MeV low-lying state.